Abstract： Objective:To assess the influence of coronary vessel dominance on myocardial perfusion imaging (MPI) by SPECT.Methods:A total of 97 patients who performed exercise stress/rest SPECT MPI in Fuwai Yunnan Hospital, Chinese Academy of Medical Sciences from August 2019 to June 2022 were retrospectively analyzed. The patients included 52 males and 45 females, aged (55.9±11.5) years. Coronary dominance was determined by coronary angiography or coronary artery contrast CT. They were divided into two groups according to the coronary vessel dominance: a dominant right coronary artery group (DRCA, n=87) and a non-dominant right coronary artery group (NDRCA, n=19), including a left-dominant coronary artery and a balanced coronary artery. The American Heart Association 17-segment model was used to analyze the MPI images of the two groups of patients, and the differences in stress/resting perfusion scores of each myocardial segment were calculated. The Wilcoxon rank-sum test was used to compare the differences in perfusion scores between the two groups. Results:Among the total of 97 patients, 63 (64.9%) showed radioactive uptake defects on the MPI images. The summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS) in the NDRCA group were significantly higher than those in the DRCA group: SSS (2 (1, 4) vs. 1 (0, 2) score), SRS (1 (1, 2) vs. 0 (0, 1) score), and SDS (0 (0, 2) vs. 0 (0, 0) score). The differences were statistically significant ( Z=-2.969, -2.945, and -2.109, respectively; all P<0.05). There were no significant differences in the scores of the apical, anterior, lateral, and septal walls between the two groups ( Z=-1.108 to 0.000, all P>0.05). The perfusion scores and ischemia rate in the inferior wall were significantly higher in the NDRCA group. Among them, the SSS, SRS, and SDS of the inferior wall of the NDRCA group were 1(0, 3)、0(0, 2) and、0(0, 1) score, respectively, which were significantly higher than those of the DRCA group at 0 (0, 0)、0(0, 0) and 0(0, 0) score, the differences were statistically significant ( Z=-3.093, -2.938, and -2.813, respectively; all P<0.05). The positive rate of inferior wall myocardial ischemia in the NDRCA group (4/19, 21.1%) was higher than that in the DRCA group (5/78, 6.4%), and the differences were statistically significant ( χ2=3.892, P=0.049). Conclusions:A significant difference in myocardial perfusion was found between patients with varied coronary vessel dominance. Patients with NDRCA had higher perfusion scores in the inferior wall on SPECT MPI. This result indicates that when the inferior wall presents a mild radioactive uptake defect, information about coronary vessel dominance may need to be considered to reduce the potential for false-positive diagnoses.